docs: def equal(self, what, epsilon=None):
          """compares given object ``X``  with an expected ``Y`` object.
  
          It primarily assures that the compared objects are absolute equal ``==``.
  
          :param what: the expected value
          :param epsilon: a delta to leverage upper-bound floating point permissiveness
          """
  
          try:
              comparison = DeepComparison(self.obj, what, epsilon).compare()
              error = False
          except AssertionError as e:
              error = e
              comparison = None
  
          if isinstance(comparison, DeepExplanation):
              error = comparison.get_assertion(self.obj, what)
  
          if self.negative:
              if error:
                  return True
  
              msg = '%s should differ from %s, but is the same thing'
              raise AssertionError(msg % (safe_repr(self.obj), safe_repr(what)))
  
          else:
              if not error:
                  return True
              raise error